AC Grayling, academic philosopher and founder of a new university college in central London, is a prolific author of books on a wide range of ethical issues. His Among the Dead Cities (2006), a study of area bombing during the second world war, accused the Allies of crimes against humanity. In works such as the secularist anthology The Good Book (2011), he has made common cause with the New Atheism of the late Christopher Hitchens and Richard Dawkins. His thoughts on humanism versus religion consequently merit our attention.

Pluralist societies, Grayling insists in The God Argument, are founded on the humanist ideal of toleration. Individuals and groups of individuals should be allowed to pursue their freely chosen values and belief systems under laws that protect freedom of conscience and speech. The opposite notion – that values and beliefs should be imposed from the top down – is the way of totalitarianism and religion.

Grayling is right to point out that, left to themselves, religions are not good at respecting rival faiths or indeed atheism: they are inherently authoritarian. Any religion worthy of the name believes itself to be the unique repository of truth, hence toleration risks a descent into relativism, or indifferentism – the notion that any one religion is as good or bad as any other. Fear of loss of authentic conviction through the influences of secularism and pluralism prompts reactive fundamentalism.

Religion’s rival truth claims, and survival fears, he observes, have been a source of conflict and violence down the ages: the Inquisition, the Crusades, Northern Ireland, 9/11. My only problem with Grayling’s argument on pluralism is his tendency to be dogmatic in his condemnations. The thrust of this book is that religion should be banned.

Much of the early part of The God Argument attacks the stock proofs for the existence of God, from St Anselm’s medieval ruminations on the nature of the greatest being, to William Paley (1743-1805) and his argument for a designer God. Grayling tells us about Freud’s theory of infantilism and the origins of religion; the effects of early religious training on faith into adulthood; the failure of metaphysics as a logical system; and the supremacy of reason over faith. He reflects on superstition and taboo in early history, and the manner in which theologians pick from scripture what suits, and ignore what doesn’t. All these excursions serve to inform religionists how stupid, ignorant, and dangerous they are.

So who is this book for? It would hardly appeal to those already convinced of atheism and humanism, for there is nothing new here. Nor does it have the sheer writing power of a Hitchens or Dawkins. It appears to have been written, in fact, for the conversion of religionists. But they will hardly appreciate being told from cover to cover what appalling chumps they are. In any case, surely most religious people do not base their beliefs on the sort of arguments – Anselm and Paley, for example – that he demolishes with such relish.

Perhaps he has written the book with students of religion in mind, to persuade them to switch to a more sensible, less pernicious subject. Yet his treatment of theology, anthropology of religion and history of religion betrays scant acquaintance with the critical and comparative uses to which they are routinely put, even in introductory courses. He seems unaware, for example, that in theological colleges the notorious five proofs for the existence of God are usually studied, if at all, in order to demonstrate their fallacious logic by modern standards of natural theology and philosophy of religion. He seems unaware that even Thomas Aquinas provided a demolition of his own proofs, indicating that faith in God lies elsewhere.

There is another reason why I would not recommend this book to students. On the second page we find the Latin tag sine qua non rendered as sine quo non; then we find the anti-slavery campaigner Frederick Douglass speaking of those who “depreciate agitation” instead of “deprecate agitation”; then we find Oscar Wilde’s elegant remark, “A map of the world that does not include Utopia is not worth even glancing at” enfeebled by Grayling’s paraphrase (“much quoted”, as he puts it): “every one’s map of the world should have a Utopia on it.” One of the many advantages of search engines is the ease with which we can check our quotes.

Grayling has made serious academic contributions to studies in moral philosophy and ethics, as well as in criticism of metaphysics and epistemology – technical areas of philosophy that deal with “how we know”. One gets the impression, however, that, fastidious as he may be on his own turf, he is a bit of a clodhopper when venturing beyond.

Apart from anything else, he does not begin to grasp what religion means for most people: why they think, or feel, that it contributes to the fulfilment of their lives. For most people the confirmation of their beliefs and practices is not based on being brainwashed as a child, as Grayling assumes. People who continue with their religion into adulthood tend to speak of spirituality rather than convictions about propositions. Spirituality, moreover, is more a function of religious imagination than ratiocinations that can be tested by logic or empirical inquiry. A single poem by George Herbert might illustrate the point. In this sense, religion is akin to art. One does not ask whether Hamlet is true in the same sense as it might be true that I had an egg for my breakfast this morning. Spirituality, similarly, inhabits areas of experience that are immune to forensic probing.

One doubts whether the New Atheism project has had much of an effect on religionists. Reading this book, it struck me that for those wavering between atheism and religion, belief might seem a more attractive option. Yet in the New Atheism genre, there has been, I believe, a lost opportunity. While it is patently true that religion from time to time has been a source of great harm, it is also true that religion has been a source of great beneficence. At what point, and by what mechanism, does religion turn from benign to malefic? By condemning all religion tout court, the New Atheists, Grayling no exception, have tended to neglect that crucial question – answers to which might be of benefit to us all.